1. Field of the Invention
The present invention relates to a circuit arrangement for connecting telex subscribers, which are connected to a data exchange system, to teletex subscribers which are likewise connected to the data exchange system. More particularly, the invention relates to a circuit arrangement which employs at least one signal converter which is connected to the data exchange system and in which the digital signals transmitted from the telex subscriber stations are converted so as to enable the same to be processed by the teletex subscriber stations, and in which the digital signals transmitted from the teletex subscriber stations are converted so as to enable the same to be processed by the telex subscriber stations.
2. Description of the Prior Art
A circuit arrangement of the type generally set forth above is already known in the art from the German Offenlegungsschrift No. 29 12 649. In this known circuit arrangement, the digital signals emitted from the relevant subscriber station are, first of all, fully received and intermediately stored in the signal converter, whereupon, during the course of the transmission of these signals, the actual signal conversion takes place. If a subscriber station which is to receive the digital signals is not currently attainable, so that the relevant digital signals cannot be deposited, the digital signals remain intermediately stored in the signal converter. However, this means that the signal converter is then blocked from being included in further connections between telex subscriber stations and teletex subscriber stations.
In order to avoid the above-described difficulty with respect to blockage, it would be possible to proceed in such a manner as to limit the maximum seizure time of the signal converter. However, this sort of procedure is not possible when it is important that the digital signals intermediately stored in the signal converter should not be lost.
It would also be conceivable that, in the event that the digital signals cannot be deposited, the digital signals intermediately stored in the signal converter may be returned to the subscriber station from which they were previously transmitted. However, this measure will not be used in view of the fact that this subscriber station merely requires confirmation of the inaccessibility of the subscriber station applied as a receiving subscriber station. In addition, it can occur that the subscriber station which previously transmitted the aforementioned digital signals is likewise no longer accessible, for example due to the absence of its subscriber number (in the case of telex subscriber stations) or due to an operating fault. Furthermore, charging technicalities can render it undesirable to return the signals in question in this manner.